Answer:
1) B a compound
2) C a heterogeneous mixture
3) A an element
Explanation:
1) I know this because a compound is mixture of different elements which cannot be identified by the naked eye. And from the statement above the substance is distinguished to have to different elements by its chemical formula.
2) I know this because a heterogeneous mixture is a mixture composed of two or more elements which can easily be seen by the physical eye or can be distinguished easily.
3) I know this because noble gases are not a mixture of any kind. They are elements. Elements are substances that cannot be broken down into simpler substances.
